POCKET GOPHEBS 137 



Gopher workings can easily be distinguished from, those made by moles. 

 Mole mounds never show an open tunnel at any time, even during con- 

 struction; the animals themselves never come out on the surface when 

 pushing out earth (fig. 22.) The earth is pushed straight up from the 

 initial opening and new earth is placed only beneath the pile already 

 started, with the result that the pile is raised still higher. In rising, the 

 earth at the top separates and keeps toppling over, leaving a peculiarly 

 porous or cleft surface (pi. 286), with no indication of the location of the 

 burrow from which the earth was extruded. And so it is that the concentric 

 'moraines' which characterize the gopher workings are never to be seen 

 on the mounds of moles. 



::Wm. Iff' 



Fig. 23. Illustrates method used by Pocket Gopher in removing earth from burrow. 

 Note that each load of earth is brought up from below and shoved out on top of the 

 ground opposite the mouth of the open ' ' lateral. ' ' The pushing out of successive loads 

 in different directions from the mouth of one lateral gives the surface mound a semi- 

 circular outline as viewed from above. Compare with plate 28. 



In addition to their characteristic mounds, pocket gophers often afford 

 much less conspicuous evidences of their activity, especially during the dry 

 season. At frequent intervals circular openings in the ground are to be 

 seen, which have been filled with loose earth nearly or quite to the level of 

 the surrounding surface. These burrows have been used as exits from short 

 side branches of the main subterranean tunnels, for the purpose of explor- 

 ing the immediately adjacent surface for food. Gophers are exceedingly 

 loath to leave shelter and ordinarily do not venture so far even as the 

 length of their bodies from the open mouths of their burrows (pi. 29a). 

 As an evident result of this timidity, each feeding exit becomes the center 

 of a small circle, shorn of vegetation, the radius of which is less than the 

 body length of the gopher. The haunches of the animal remain in contact 

 with the orifice of the burrow as a sort of anchor by means of which he can 

 pull himself back into safety at an instant's warning. It is well known 

 to gardeners that a gopher will burrow underground some distance to a 

 plant rather than risk capture by venturing forth on the surface even a 



